The invention relates to a flexible polyolefin compound for use in floor coverings or upholstery where a low gloss, highly flexible, soft and thermoformable material is desired. The invention is particularly useful for vehicle floor covering made with recycled and reclaimed waste polymeric material.
There has been an increased interest in recycling, reclaiming and reutilizing waste and scrap material, and particularly waste thermoplastic polymeric material obtained from a variety of sources. This is partly due to increasing costs of storage and/or landfill space and more stringent regulations for disposal or incineration.
The vehicle manufacturers have aggressively participated in recycling efforts. For example, Ford Motor established its Recycling Action Team in 1991 to find ways to increase the use of recycled materials in its vehicle manufacturing. Outcomes of this program include Visteon Automotive Systems' recycling of thermoplastic scrap from automobile bumpers and E.I. Dupont's recycling of scrap into automobile air cleaners.
The recycling of most mixtures of thermoplastic scrap material is limited by the incompatibility of the various different kinds of thermoplastic material present in the scrap. For example, the various thermoplastic resins are often insoluble in each other resulting in a heterogeneous mixture in which each type of resin forms a dispersed phase in the other. This often results in adversely affecting the mechanical properties (e.g., tensile and impact strength) and aesthetic properties of any articles formed from such a mixture.
Processes for recycling floor covering scrap are desired inasmuch as a particularly large amount of scrap material is generated during the manufacture and installation of floor covering. For example, during installation of automotive interior carpet, a quantity of carpet remnant is generated as the carpet is formed and cut into various irregular shapes. As a result, millions of pounds of thermoplastic scrap waste are generated every year as part of the automobile manufacturing process. Similarly, installation of residential or commercial floor coverings generates comparable waste sources.
Typical floor covering scrap contains polyamides (for example nylon 6 and nylon 6,6), polyester, polypropylene, poly(ethylene-co-vinyl acetate), hereinafter EVA, and varying amounts of fillers such as CaCO3 and BaSO4. Each of the polymers has its own physical and chemical properties, and therefore different processing conditions. For example, ethylene-vinyl acetate copolymer (EVA) begins to degrade at 190°-200° C. releasing acetic acid in the process. Since EVA is a major component of floor covering scrap, serious consideration must be given to the processing temperature. Polypropylene has a melt temperature of about 165° C. while the polyamide nylon 6,6 has a melt temperature of 265° C. To prepare blends of EVA and polypropylene materials, one would ideally operate between about 210° C. and 230° C.; however, EVA degradation may prevent operation at such high temperature.
Other attempts have been made to recycle the thermoplastic compounds found in floor coverings. U.S. Pat. Nos. 6,099,775 and 5,883,020 to Bargo et al, uses 1 to 30% of such thermoplastic scrap in the formation of insulation (thermoplastic scrap containing nylon fibers and other materials such as ethylene-vinyl acetate, polyvinyl chloride, or polypropylene). The Bargo application mixes scrap with fiberized glass fibers and phenolic resins to form an insulation material. Other resins such as epoxy resins, vinyl esters, and urethane silicones may also be utilized. U.S. Pat. No. 4,029,839 to Lesti also discloses the use of thermoplastic scrap in the formation of insulation products.
U.S. patents to Sifniades et al (U.S. Pat. Nos. 5,932,724; 5,929,234 and 5,681,952) teach depolymerization techniques for obtaining caprolactum from the nylon contained in thermoplastic scrap.
U.S. Pat. No. 4,968,463 to Levasseur proposes shredding or granulating polymeric waste, drying the material to a water content of not more than 8% by weight, preheating the material to a temperature of 80.degree. C. to 160.degree. C., kneading at a temperature of 120.degree. to 250.degree. C. and injection molding or extrusion of the material to form a product such as a fence post.
U.S. Pat. No. 5,889,142 to Mohajer et al. discloses the recovery of polyamide from the nylon contained in thermoplastic scrap. The recovered polyamide is then available for feedstock in new nylon fiber manufacture.
U.S. Pat. No. 5,728,741 to Zegler et al. discloses the use of thermoplastic scrap in the form of automotive carpet scrap in the manufacture of compositions useful as floor coverings, particularly the secondary backing used in carpet manufacture. Similarly, U.S. Pat. No. 4,663,103 to McCullough et al. also discloses a method of processing such scrap into carpet backing.
U.S. patents to David et al. (U.S. Pat. Nos. 5,591,802; 5,498,667 and 5,294,384) create a thermoplastic product by forming a melt blend from thermoplastic scrap at a temperature of 250° C. to 260° C. The thermoplastic product is typically pelletized and used as a raw material in other products. The David patents disclose that additional polymers can be added to the melt blend but do not teach how a particular polymer will meet product specifications.
U.S. patents to Young, et al (U.S. Pat. Nos. 5,859,071; 5,852,115 and 5,719,198) also disclose preparing products from a melt blend using thermoplastic scrap and polymers, particularly ethylene-co-vinyl acetates. Resultant compositions are indicated as being useful as general-purpose commodity thermoplastics. These patents also disclose the addition of polypropylene in amounts of 1% to 10% to the melt blend in order to create a “rigid” material.
However, in contrast to rigid materials, it is desirable to create flexible thermoplastics comprised of recycled thermoplastic scrap and polypropylene for use in vehicles to satisfy preferences for recycled compositions. Such thermoplastics are useful for interior coverings such as floor coverings and dashboards as well as exterior uses such as truck bed liners. For example, U.S. Pat. No. 6,099,771 to Hudkins, et al. discloses a method of creating floor mats for automobiles.
Vehicle manufacturers set a number of requirements that suppliers of thermoplastic materials must satisfy. The Hudkins patent discloses the requirement that automobile parts should have a high quality surface finish described as “Class A” that is free of imperfections. In addition, vehicle interiors can attain elevated temperatures due to sunlight transmission into an unventilated interior. Thermoplastic compositions used in such environments must be thermally stable yet not release excessive levels of compounds that can condense on interior surfaces such as windows.
Accordingly, there is a need in the industry for thermoplastic compositions comprised of a blending stock that can combine with thermoplastic recycle scrap available from such sources as floor coverings. Additionally, there is a need for thermoplastic compositions comprising recycle scrap where such compositions are useful in vehicle applications. Such needs for recycling are not limited to vehicle applications and would also apply to any industry that may utilize such resultant compositions.